A COMPARISON OF POINTS VERSUS SOUNDS AS REINFORCERS IN HUMAN OPERANT RESEARCH THESIS. Presented to the Graduate Council of the

Transcription

1 3"H *81 -*o. 76/y A COMPARISON OF POINTS VERSUS SOUNDS AS REINFORCERS IN HUMAN OPERANT RESEARCH THESIS Presented to the Graduate Council of the University of North Texas in Partial Fulfillment of the Requirement For the Degree of MASTER OF SCIENCE By Susan L. Rouse, B.S. Denton, Texas August, 1999

2 Rouse, Susan L, A comparison of points versus sounds as reinforcers in human operant research. Master of Science (Behavior Analysis), August, 1999, 73 pp., 6 tables, 10 illustrations, references, 29 titles. Research shows that human operant behavior typically differs from non-human operant behavior on schedules of reinforcement. These differences in performance may be related to differences between the experimental preparations used to study human and non-human operant behavior. One such difference is the type of reinforcer used. This experiment analyzed the differential effects of points alone, points backed up by money, and sounds on schedule performance of human subjects. Results show that sounds generated moderate rates of responding, capable of change in either direction. When points backed up with money were the reinforcers, however, high rates of behavior were generated, disrupting the previously established baseline performance. This suggests that while points may be effective in generating high rates of behavior, they may be ineffective in producing sensitive baselines needed to study human operant behavior on schedules of reinforcement.

3 3"H *81 -*o. 76/y A COMPARISON OF POINTS VERSUS SOUNDS AS REINFORCERS IN HUMAN OPERANT RESEARCH THESIS Presented to the Graduate Council of the University of North Texas in Partial Fulfillment of the Requirement For the Degree of MASTER OF SCIENCE By Susan L. Rouse, B.S. Denton, Texas August, 1999

4 Copyright by Susan Lynn Rouse

5 ACKNOWLEDGMENTS I would like to thank my major professor, Dr. Jesus Rosales-Ruiz for all of his advice and for making this thesis possible. I also thank Dr. Cloyd Hyten and Dr. Joel Greenspoon for all of their insightful comments and for taking the time to review the manuscript. My deepest thanks go out to Richard Anderson for his programming expertise and last-minute data analysis. Finally, I thank my parents, Bill and Diana Rouse for their constant love and support. IV

6 TABLE OF CONTENTS Page LIST OF TABLES LIST OF ILLUSTRATIONS vi vii Chapter 1. INTRODUCTION 1 2. METHOD (EXPERIMENT I) 6 3. RESULTS (EXPERIMENT I) DISCUSSION (EXPERIMENT I) METHOD (EXPERIMENT II) RESULTS (EXPERIMENT II) DISCUSSION (EXPERIMENT II) GENERAL DISCUSSION 27 APPENDIX A 31 APPENDIX B 33 APPENDIX C 35 APPENDIX D 56 REFERENCES 69

7 LIST OF TABLES Page Table 1. Session information for subject LWSP99 57 Table 2. Session information for subject BBSP99 59 Table 3. Session information for subject LGSP99 61 Table 4. Post-reinforcement-pause (PRP) data for subject LWSP99 63 Table 5. Post-reinforcement-pause (PRP) data for subject BBSP99 65 Table 6. Post-reinforcement-pause (PRP) data for subject BBSP99 67 VI

8 LIST OF ILLUSTRATIONS Page Figure 1. Experimental apparatus 36 Figure 2. Change in apparatus when target response is made 38 Figure 3. Cumulative records for subject JTSP99 40 Figure 4. Cumulative records for subject LSSP99 42 Figure 5. Standard celeration chart for subjects in Experiment I 44 Figure 6. Acquisition for subjects in Experiment II 46 Figure 7. Cumulative records for subject LWSP99 48 Figure 8. Cumulative records for subject BBSP99 50 Figure 9. Cumulative records for subject LGSP99 52 Figure 10. Standard celeration chart for subjects in Experiment II 54 vu

9 CHAPTER 1 INTRODUCTION A Comparison of Points vs. Sounds as Reinforcers in Human Operant Research Research shows that human operant behavior typically differs from non-human operant behavior on schedules of reinforcement. Human behavior tends to show persistence of certain response patterns despite changes in the schedule parameters. Nonhuman behavior, on the other hand, shows orderly and systematic relations between the response and the schedule parameters. These differences in performances may be related to differences between species and differences between the experimental preparations used for studying human and non-human behavior (Baron & Perone, 1998; Home & Lowe, 1993; Lattal & Perone, 1998; Lowe, 1979; Shull & Lawrence, 1998; Wearden, 1988). One such difference in experimental preparations is the reinforcer used. Whereas food pellets have typically been used as reinforcers in non-human operant research (Ferster & Skinner, 1957), points have frequently been used as reinforcers in human operant research (Baron, Kaufman & Stauber, 1969; Catania, Matthews & Shimoff, 1982; Galizio & Buskist, 1988; Hayes, Brownstein, Zettle, Rosenfarb & Korn, 1986; Joyce & Chase, 1990; Matthews, Catania, Shimoff & Sagvolden, 1977; Rosenfarb, Newland, Brannon & Howey, 1992; Weiner, 1962, 1969).

10 Shull and Lawrence (1998) cautioned against assuming functional similarity between procedures used to study non-human operant behavior and human operant behavior. One of their focal points concerned the functional similarity between types of reinforcers used in human and non-human operant research. They pointed out that food pellets, like points, are discrete events that can be delivered immediately following the completion of the response requirement. However, food, unlike points, has a biological basis in that it is an item necessary for survival and can be consumed by the organism immediately following its delivery. It is also possible to control for the effectiveness of food as a reinforcer by maintaining consistent deprivation levels prior to the beginning of each experimental session. It is commonly acknowledged that points are conditioned reinforcers that subjects accumulate and exchange at the end of an experimental session or even at the end of an experiment, for money or prizes (Catania, 1992; Hyten, Madden & Field, 1994; Shull & Lawrence 1998; Wearden, 1988). Experimenters have established points as conditioned reinforcers either by telling the subjects the monetary value of each point (Baron et al., 1969; Catania et al., 1982; Hayes et al., 1986; Joyce & Chase, 1990; Matthews et al., 1977), or by instructing subjects to earn as many points as possible (Rosenfarb et al., 1992; Weiner, 1962). However, the effects that points alone and points backed up by money have on human operant behavior have been largely unexamined (Galizio & Buskist, 1988). It has even been suggested that points may be weak reinforcers, easily overridden

11 by other experimental variables, or that they are not even effective as reinforcers for some subjects (Matthews et al., 1977). One difficulty that points present to laboratory research is that they are usually established as conditioned reinforcers prior to the experiment. Points pervade most aspects of human life and most humans, especially college students who have typically been the population under study, encounter points every day. From an early age, humans have learned to associate points, specifically a higher number of points, with success, achievement, and winning. When a person has played a video game, has watched a sporting event, or has taken an exam, the person or team with the most points has emerged as the winner. Points, when brought into the experimental preparation, may carry with them an underlying instruction: "Earn as many points as you can", regardless of any schedule that may have been programmed by the experimenter. Indeed, an additional instruction may be needed to override the history subjects have had with points in order to gain experimental control. Another difference between points and food is that points are sometimes presented as a running total displayed on a counter. This introduces a potential source of control as the growing total may signal progress made toward the end of an experimental session or toward a specified amount of points the subject wishes to earn during a session (Shull & Lawrence, 1998).

12 Wearden (1988) suggested that point deliveries, when accompanied by a visible counter, could fall under the category of informational feedback as the counter provides feedback to the subjects regarding their performance. He also suggested that behavior under the control of this informational feedback is less likely to change systematically with changes in contingencies. Instead, when behavior is maintained by informational feedback rather than classical reinforcers, abrupt changes in both response rate and response patterns are likely to occur when contingencies are changed. Given the difficulties that points present to the laboratory, some researchers have advocated the use of other reinforcers that occur naturally in the environment and are more likely to reinforce when they are presented rather than at the end of the experiment (Baron & Perone, 1998; Galizio & Buskist, 1988; Shull & Lawrence, 1998). Events that have been used include video games (Baum, 1975; Case, Ploog & Fantino, 1990; Millar & Navarick, 1984), brief clips of a cartoon (Baer, 1960; Darcheville, Riviere & Wearden, 1993), focusing slides (Benton & Mefferd, 1967), picture viewing (Navarick, 1986) and sound clips of music, movies, television shows and comedy skits (Rosales-Ruiz, Anderson, Hensley & Koremura, 1999). The purpose of this study is to analyze the differential effects of points alone, points backed up by money, and sounds on schedule performance of human subjects. Do points alone and points backed up by money generate similar response rates and response patterns as those generated by sounds? The first experiment examines the effect of

13 changing the reinforcer from points without a monetary value, to sounds when behavior is maintained on a continuous schedule of reinforcement. A second experiment examines the effect of changing the reinforcer from sounds to points with a monetary value when behavior is maintained on an FR5 schedule of reinforcement.

14 CHAPTER 2 METHOD Experiment I Subjects and Setting Two undergraduate college students (LSSP99 and JTSP99) from the University of North Texas participated in this experiment. These subjects were recruited through an advertisement that had been posted in several locations around the University campus (see Appendix A). Neither of the subjects had ever taken a course in behavior analysis. Subjects earned $5.00 for each 20-min session. All money earned was paid to the subjects upon completion of the experiment and was independent of their performance. The experiment was conducted in a University laboratory that contained a table upon which a computer monitor, keyboard, headphones and mouse were placed. The subject was alone during the session. Each session lasted 20 minutes. Only one session per day was run for each subject in order to maximize the effectiveness of the reinforcer and to decrease the likelihood of fatigue. Apparatus The apparatus consisted of an Intel Pentium-based IBM compatible computer, monitor, mouse, and numerical keypad located on the keyboard. The target response

15 consisted of the subject pressing the numerical sequence on the number keypad in that order. A 3 x 3 grid was displayed on the computer monitor during the experiment. Each square on the grid corresponded to the number on the keyboard. The entire grid was approximately 8 cm 2 and each individual square within the grid was approximately 2 cm 2. Each square resembled a three-dimensional button and was separated from the other buttons by 0.5 cm. A border enclosed the entire grid. When the experiment began, all squares appeared "popped out" and light gray in color (see Figure 1). The squares changed their appearance from "popped out" to "pressed in", if keys were pressed from left to right. Other key strokes produced no change in the grid (see Figure 2). Located just below the grid on the computer monitor was a 5.5-cm square that appeared to be "beveled". Under certain experimental conditions, a button with a speaker icon appeared in the beveled area. Either a point or a sound clip varying in length from 0.38-sec to 4-sec was produced when the subject clicked on this button with the mouse. During conditions where points were delivered as consequences, a numerical counter displayed just above the grid increased by one. Sounds were delivered through the headphones the subject wore during the experiment. These sounds consisted of soundbytes taken from music, movies, television shows and comedy skits.

16 8 Dependent Variable The dependent variables consisted of the frequency of responses (cumulative response curves) and the changes in rate of response (celeration of responding). Independent Variable The independent variable consisted of a change in consequence from points (with no monetary value) to sounds. Procedure Acquisition of response. In the first session of the experiment, once the subject was seated in front of the computer, the experimenter read the following instructions out loud: The experimenter pointed to the nine keys located on the keypad portion of the keyboard and at the same time said, "Press any of these nine keys". (The experimenter then pointed at the computer screen to a beveled area below the 3 x 3 grid) "Occasionally a button will appear here. When it does, click it with the mouse". The experimenter then handed a pair of headphones to the subject and said, "Please wear the headphones at all times." If the subject asked the experimenter any questions, the i nstructions were simply repeated from the beginning. After the instructions were delivered, the experimenter left the room.

17 The key presses in left to right order were shaped by the computer. When the subject initially pressed a key in the left-column (e.g., 1, 4, or 7), the corresponding grid square on the computer screen changed from "popped out" to "pressed in". If the subject pressed a key in the middle column (e.g., 2, 5, or 8) or the right column (e.g., 3, 6, or 9) before pressing a key in the left column, no change was produced in the grid. Additionally, after one press in the left column was made, pressing another number in the same column did not produce an effect for that trial. For example, if the subject pressed the number 4, pressing keys 1, 4, or 7 again did not change the grid. In order to produce the next change in the grid, the subject was required to press a key in the middle column (e.g., 2, 5, or 8). When the subject pressed one of these numbers, the corresponding square on the grid also changed from "popped out" to "pressed in". Pressing another key in the same column or in the left-hand column (e.g., 1, 4, or 7) did not produce an effect. After this step was completed, the only response that produced a change in the grid was a key press of one of the numbers in the right-hand column (e.g., 3, 6, or 9). Upon completion of the initial left-to-right sequence, the subject was required to press a number in the left-hand column (e.g., 1, 4, or 7) in order for the grid to reset. When the grid reset, all of the grid squares appeared "popped out" except for the square corresponding to the number in the left-hand column the subject had just pressed. This square then appeared to be "pressed in" and changed color from light gray to dark gray. The subject could continue to press any left to right sequence, and the corresponding grid squares would change colors, but no consequences were delivered until the subject made

18 10 the target response When the subject pressed the target response during the initial shaping procedure (Fixed-Ratio 1), the following changes occurred: (a) a sound, called the "hopper sound" was played; (b) a button appeared just below the 3 x 3 grid; and (c) when the button was "clicked" with the mouse, either a point was delivered or a random sound from a bank of 283 unique sound-clips was played, depending on the experimental condition. If any other key sequences were typed, no sound events occurred and no consequences were delivered. Design Subjects JTSP99 and LSSP99 were exposed to an FR1 schedule of reinforcement using points without a monetary backup as reinforcers before the sounds were introduced according to a multiple baseline design across subjects. Changes in conditions took place after at least 2 sessions with similar performances occurred. Similarity was judged by visually inspecting the cumulative records across sessions.

19 CHAPTER 3 RESULTS Experiment I Figure 3 shows subject JTSP99 performances under an FR1 schedule of reinforcement when points without a monetary backup (points alone) and sounds were used as reinforcers. The numbers to the left of the curves indicate the session number. The rate of responding during the FR1 - points alone condition increased from session 1 to session 2. The subject emitted 27 responses per minute during session 1 and responses per minute during session 2. The rate of responding then declined slowly during sessions 3 (40.15 responses per minute) and 4 (37.55 responses per minute). When the sounds were introduced, however, the rate of responding increased. During session 5, the rate of responding was 47.3 and increased to the highest rate of 57.9 during session 6. Session 7 shows a slight decrease in the rate of responding (44.9 responses per minute) and an increase during session 8 (52.05 responses per minute). In general, the subject responded at a constant rate with few breaks during both reinforcer conditions. Figure 4 shows subject LSSP99 performances under an F'Rl schedule of reinforcement when points without a monetary backup and sounds were used as reinforcers. The numbers to the left of the curves indicate the session number. The rate of responding during the FR1 - points alone condition increased from session 1 to session 11

20 12 2. During session 1, the subject emitted responses per minute and responses per minute during session 2. Beginning with session 3, this subject either responded at high rates throughout the session or had periods of high responding followed by periods of no responding during other sessions. The overall rate per minute for sessions 3-6 were as follows: 41, 132.5, 48.2, and When the sounds were introduced, the subject continued to respond at the high rates seen during the points alone condition in sessions 7 (140.9 responses per minute) and 9 (120.3 responses per minute) and responded at very low rates in sessions 8 (5 responses per minute) and 10 (1.8 responses per minute). Figure 5 shows the changes in rate of responding across sessions for subjects JTSP99 and LSSP99. During the FR1 - points alone condition, JTSP99 (left) had a range of responding from 27 responses per minute in session 1 to responses per minute in session 2. During the FR1 - sounds condition, the range of responding was from 44.9 responses per minute in session 7 to 57.9 responses per minute in session 6. Based on the range, this subject was less variable when sounds were the reinforcers. During the FR1 - points alone condition, subject LSSP99 (right) had a range of responding from 41 responses per minute in session 3 to responses per minute in session 2. During the FR1 - sounds condition, the range of responding was from 1.8 responses per minute in session 10 to responses per minute in session 7. Based on the range, this subject was more variable when sounds were the reinforcers.

21 CHAPTER 4 DISCUSSION Experiment I The delivery of points without a monetary backup on a continuous schedule of reinforcement generated either high rates of responding mixed with periods of no responding in one subject (LSSP99), and constant, moderate rates of responding in the other subject (JTSP99). Overall, these results support the notion that the accumulation of points alone can be a reinforcer (Galizio & Buskist, 1988; Shull & Lawrence, 1998). That is, they can shape and maintain behavior. However, given the variability in responding between subjects and within a subject, points do not seem to be reliable reinforcers in generating consistent performances that could be used to establish a sensitive baseline when they are presented alone. Backing up the points with money may produce more consistent performances across subjects and within subjects. Even if sources of variability still remain in subjects' training histories with respect to money, at least the backup reinforcer will be common across subjects. When sounds were introduced during Experiment I, they slightly increased the rate of responding for JTSP99 and significantly increased the range of responding of LSSP99. These results suggest that sounds, although different in their effect from points without a monetary backup, are not more reliable reinforcers than points alone in 13

22 14 producing consistent performances within subjects. However, the performances produced by sounds in this experiment look uncharacteristic when compared to performances produced in other research where sounds were the only reinforcer used (e.g., Rosales-Ruiz et al., 1999). In research conducted by Rosales-Ruiz et al., sounds consistently produced a smooth, constant rate of performance between responses per minute during FR1 conditions. The temporal sequence of points alone and sounds may be related to the high rate of responding associated with sounds. Experiment II explores the above possibilities.

23 CHAPTER 5 METHOD Experiment II The second experiment examined the effects of changing the reinforcer from sounds to points with a monetary value when behavior was maintained on an FR5 schedule of reinforcement. Subjects and Setting Three undergraduate male college students (LWSP99, BBSP99 and LGSP99) from the University of North Texas participated in this experiment. These subjects were recruited through an advertisement that had been posted in several locations around the University campus (see Appendix A). None of the subjects had ever taken a course in behavior analysis. During the Fixed-Ratio 5 - sounds conditions, all subjects earned $5.00 independent of their performance. During the FR5 - points/money condition, each point earned was worth 2 cents. All money earned was paid to the subjects upon completion of the experiment. The apparatus, session length and initial instructions were identical to those used in Experiment I. 15

24 16 Dependent Variable The dependent variables consisted of the frequency of responses (cumulative response curves), changes in rate of response (celeration of responding) and postreinforcement pause (PRP). Independent Variable The independent variable was the kind of consequence, including the addition of a verbal instruction associated with the points/money condition: "During this condition you will earn points instead of sounds. Each point is worth 2 cents". Procedure Acquisition of response. The shaping procedure used during this experiment was similar to the shaping procedure used for Experiment I. The only difference during the initial shaping sequence consisted of the type of consequence used. When the subject pressed the target response 1-5-3, a random sound clip, instead of a point, was delivered. Design Subjects LWSP99 and BBSP99 were exposed to an FR5 schedule of reinforcement using sounds as consequences before the points with a monetary value were introduced according to a multiple baseline design across subjects. Subject LGSP99, on the other hand, was exposed to a baseline that consisted of repeated reversals between FR5 and FRIO schedules of reinforcement using sounds as consequences before the points with a monetary value were introduced following an FR5 schedule of

25 17 reinforcement. Changes in conditions took place after at least 2 sessions with similar performances occurred. Similarity was judged by visually inspecting the cumulative records across sessions.

26 CHAPTER 6 RESULTS Experiment II Figure 6 shows the cumulative records of the acquisition of for all 3 subjects who participated in Experiment II. For these subjects, acquisition occurred during the second experimental session and the data show a slow, steady rate of responding that is similar across all subjects. Subject LWSP99 emitted 11.3 responses per minute for a total of 226 responses; BBSP99 emitted responses per minute for a total of 239 responses and LGSP99 emitted 15.2 responses per minute for a total of 304 responses. Figure 7 shows subject LWSP99 performances under an FR5 schedule of reinforcement with sounds and points/money used as reinforcers. The numbers to the left of the curves indicate the session number. The cumulative records show that responding was stable across sessions 3-5 of the FR5 - sounds condition. During baseline session 5, LWSP99 responded at a rate of When points with a monetary value were introduced in session 6, the subject responded at a rate of 59.3 responses per minute and increased to the highest rate of responses per minute during session 8. Session 9 shows a slight decrease in the rate of responding (73.95 responses per minute). When sounds were reintroduced, the rate of responding decreased to responses per minute. In general, LWSP99 responded at a constant rate with few breaks during both 18

27 19 reinforcer conditions. Response rate increased as a function of changing the reinforcer from sounds to points/money and decreased as a function of changing the reinforcer back to sounds from points/money. Interestingly, the rate of responding in the reversal to the sounds condition was higher than the original baseline. Table 1 shows number of responses, rate per minute, points earned and money earned during each experimental session for subject LWSP99. During the points/money condition, this subject earned a minimum amount of $4.74 in session 6 and a maximum amount of $6.10 in session 8. During the sounds conditions, the $5.00 earned was independent of performance. Figure 8 shows subject BBSP99 performances under an FR5 schedule of reinforcement with sounds and points/money used as reinforcers. The numbers to the left of the curves indicate the session number. Sessions 13 and 14 are not presented for this subject. Session 13 resulted in a laboratory error whereby the subject was mistakenly placed on an FR1 schedule of reinforcement for the response topography This mistake was corrected in session 14. The cumulative records show that although there was variability within sessions 6-8 of the initial FR5 - sounds condition, the rate of responding across these sessions was similar. The overall rate for sessions 6-8 were as follows: 44.75, and When points with a monetary value were introduced, the rate of responding increased and the previous variability seen within each session was greatly reduced. During session 9, the subject responded at a constant rate of 100.6

28 20 responses per minute and the rate of responding increased to the highest rate of responses per minute by session 15. When sounds were reintroduced, the rate of responding decreased to 65 responses per minute in session 16, increased to 85.7 responses per minute in session 17 and decreased to 15.1 responses per minute in session 18. These decreases in response rate, however, represent breaks in responding rather than overall changes in speed. In general, this figure shows that the rate of responding increased as a function of changing the reinforcer from sounds to points/money and decreased as a function of changing the consequence back to sounds from points/money. The change in consequence from sounds to points/money also had the effect of drastically reducing the within session variability for this subject. The rate of responding in the reversal to the sounds condition was also higher than the original baseline for two of the three sessions. Table 2 shows number of responses, rate per minute, points earned and money earned during each experimental session for subject BBSP99. During the points/money condition, this subject earned a minimum amount of $5.00 in session 14 and a maximum amount of $12.00 in session 15. During the sounds conditions, the $5.00 earned was independent of performance. Figure 9 shows subject LGSP99 performances under an FR5 schedule of reinforcement with sounds and points/money used as reinforcers. The numbers to the left of the curves indicate the session number. The cumulative records show that the rate of responding on the FR5 - sounds condition decreased in the last two sessions. The overall

29 21 rate per minute for sessions are as follows: 83.05, 91.45, 58.4, When points with a monetary value were introduced in session 22, the rate of responding increased to responses per minute and increased to the highest rate of responses per minute by session 25. When sounds were reintroduced, the rate of responding decreased to responses per minute. In general, this figure shows that the subject responded at a constant rate with few breaks during both reinforcer conditions. Response rate increased as a function of changing the reinforcer from sounds to points and decreased as a function of changing the reinforcer back to sounds from points. Table 3 shows number of responses, rate per minute, points earned and money earned during each experimental session for subject LGSP99. During the points/money condition, this subject earned a minimum amount of $11.46 in session 22 and a maximum amount of $12.64 in session 25. During the sounds conditions, the $5.00 earned was independent of performance. Figure 10 shows the changes in rate of responding across sessions for subjects LWSP99, BBSP99 and LGSP99. Only data from the main experimental conditions are presented. During the first FR5 - sounds condition, LWSP99 (left) responded at an average of 38.8 responses per minute with a range from responses per minute to 41.7 responses per minute. When points with a monetary value were introduced, the frequency increased to an average of responses per minute with a range from 59.3 responses per minute to responses per minute. Finally, when sounds were reintroduced, the frequency decreased to an average of responses per minute with a

30 22 range from responses per minute to 51.3 responses per minute. Overall, subject LWSP99 responded times faster during the points/money condition than during the first FR5 - sounds condition. Subject BBSP99 (middle) responded during the first FR5 - sounds condition at an average of 39.3 responses per minute with a range from responses per minute to 54.7 responses per minute. When points with a monetary value were introduced, the frequency increased to an average of responses per minute with a range from responses per minute to responses per minute. Finally, when sounds were reintroduced, the frequency decreased to an average of responses per minute with a range from 15.1 responses per minute to 85.7 responses per minute. Overall, subject BBSP99 responded times faster during the points/money condition than during the first sounds condition. Subject LGSP99 (right) responded during the third FR5 - sounds condition at an average of responses per minute with a range from responses per minute to responses per minute. When points with a monetary value were introduced, the frequency increased to an average of responses per minute with a range from responses per minute to responses per minute. Finally, when sounds were reintroduced, the frequency decreased to an average of responses per minute with a range from responses per minute to responses per minute. Overall, subject LGSP99 responded times faster during the points/money condition than during the third FR5 - sounds condition.

31 23 Table 4 shows the mean and range of the post-reinforcement pauses (PRP) during each session for subject LWSP99. All PRP's are represented in looths of a second. During the original FR5 - sounds baseline condition, this subject had an overall average PRP of with a range from in session 2 to in session 3. During the FR5 - points/money condition, this subject had an overall average PRP of with a range from in session 8 to in session 6. During the reversal to FR5 - sounds, this subject had an overall average PRP of with a range from in session 10 to in session 12. Table 5 shows the mean and range of the post-reinforcement pauses (PRP) during each session for subject BBSP99. All PRP's are represented in looths of a second. During the original FR5 - sounds baseline condition, this subject had an overall average PRP of with a range from in session 6 to in session 5. During the FR5 - points/money condition, this subject had an overall average PRP of with a range from in session 15 to in session 14. During the reversal to FR5 - sounds, this subject had an overall average PRP of with a range from in session 16 to in session 18. Table 6 shows the mean and range of the post-reinforcement pauses (PRP) during each session for subject LGSP99. All PRP's are represented in looths of a second. During the third FR5 - sounds baseline condition, this subject had an overall average PRP of with a range from in session 19to in session21. During the

32 24 FR5 - points/money condition, this subject had an overall average PRP of with a range from in session 25 to in session 22. During the reversal to FR5 - sounds, this subject had an overall average PRP of with a range from in session 27 to in session 29.

33 CHAPTER 7 DISCUSSION Experiment II The results of Experiment II show that the rate of responding increased as a function of changing the consequence from sounds to points with a monetary value and decreased as a function of changing the consequence from points/money to sounds. Overall, these results support the notion that the accumulation of points with a monetary value produce consistent performances within subjects (Galizio & Buskist, 1988). Additionally, all subjects showed a step-like moderate rate of performance with pauses after reinforcement when sounds were introduced before points/money. When the reinforcer was changed to points/money, all subjects showed a constant, high rate of performance, with little pausing after reinforcement, similar to the patterns generated by human subjects on variable-ratio schedule of reinforcement in other experiments (e.g., Matthews et al., 1977). In contrast to the first experiment, the response rates across all subjects during the second experiment were considerably lower during the first two sessions of acquisition when sound was the reinforcer. Additionally, the response rates generated by the FR5 - sounds schedule during this experiment only reached levels as high as the lowest response rate generated by the FR1 - points condition in the first experiment. 25

34 26 The reversal back to sounds resulted in a decrease in the rate of responding for all three subjects. These decreases, however, represented two different patterns of responding, as seen in the cumulative records. For two of the subjects, the rate of responding systematically decreased towards baseline levels. For the other subject (BBSP99), the decrease in responding was a result of abrupt breaks in responding mixed with periods of sustained high rates of responding similar to the ones seen in the FR5 points/money condition. In general, this study shows that points, when backed up by money, generated extremely high rates within subjects and consistent performances across subjects. When sounds were introduced before points on an FR5 schedule of reinforcement, the result was a moderate overall rate in responding typical of that seen in previous research (Rosales-Ruiz et al., 1999). Given that points/money tend to generate high rates of responding, the utility of these performances as baselines may be limited to variables intended to decrease behavior. However, if the purpose of research is to study the effects of independent variables that may increase or decrease behavior, it is necessary to have a baseline that is stable and has the capacity to change in either direction (Sidman, 1960). The moderate rates that were obtained when sounds were the reinforcers may provide researchers with a baseline against which the effects of such independent variables can be assessed.

35 CHAPTER 8 GENERAL DISCUSSION The present experiments compared the effects of using points alone, points backed up by money and sounds as reinforcers on human operant behavior. The results show that during Experiment I, points alone did not generate consistent performances between subjects or within subjects. Interestingly, when points alone were the reinforcer during acquisition, they produced higher rates of responding than sounds in Experiment II. In Experiment II, points backed up by money disrupted the established FR5 - sounds baseline performance for all subjects. This is seen in both the higher response rate that was generated with points/money as well as the decrease in the duration of the PRP. The high rates produced by points are not uncommon in the literature. Indeed, researchers have found it necessary to decrease them by either introducing a DRL schedule of reinforcement (Weiner, 1969); adding a response cost (Weiner, 1962); or utilizing instructions to override the effect of points (Baron et al., 1969; Catania et al., 1982; Hayes et al., 1986). Although the rates generated by sounds were more or less recovered (for some subjects) after the first reversal to sounds following points, the duration of the PRP was not. Wanchisen, Tatham and Mooney (1989) suggested that such effects may be due to the prior history of responding. They showed that when non-human subjects have a 27

36 28 history of responding at high rates, behavior does not change systematically when the contingencies are changed. It is possible that when human subjects have a history of high rates of responding with points as the consequence, the result may be persistence of response patterns even if the contingencies are changed. This, however, is still an area that needs to be examined. It is also possible that the high rates generated after the points were introduced may have dissipated during the reversal back to sounds if more sessions had been conducted with each subject. Indeed, the reversal back to FR5 - sounds from FR5 - points for subject LGSP99 shows a decreasing trend. Thus, it may be possible to recover previous performances by extending the baseline periods, as Baron and Leinenweber (1995) suggested. Further research with extended baselines should clarify the disruptive effects of points-money. Several factors have been postulated to account for these high rates. One of these factors is the subjects' ability to engage in what is commonly referred to as "self-talk". It may be that this type of verbal behavior is more likely to occur when the reinforcer used is a point. Because of the history that humans have with points, it is likely that points carry an underlying instruction: "Earn as many points as you can" (Lowe, 1979; Catania et al., 1982). Verbal factors have been one of the main variables to account for the differences in performances between humans and non-humans in schedule research. An alternative account is that these verbal factors and the correlated performances are both a product of a history of training. Instead of seeing the high rates and insensitivity

37 29 generated by points in previous research as an anomaly in performance, it could be argued that points represent a fundamentally different schedule of reinforcement that tends to generate maximal rates of performances and that overrides other scheduled contingencies, as is suggested by Experiment II. In summary, this research shows that points alone, points backed up with money, and sounds are not equivalent reinforcers. This supports the assumption that the selection of a reinforcer for an experiment is a critical factor, depending on the purpose of the experiment (Galizio & Buskist, 1988; Sidman, 1960). If the purpose of the experiment is to examine behavior under schedules of reinforcement, it is important to select a reinforcer that will produce stable, moderate rates of behavior. These moderate rates will provide researchers with a sensitive baseline, capable of change in either direction, against which the effects of other independent variables can be examined. The results of this experiment show that sounds are capable of providing researchers with such a baseline. However, if the purpose of the research is to attempt to increase the rate of behavior, points backed up with money may be an optimal reinforcer as they consistently generated extremely high rates of behavior. Historically, when researchers have examined behavior under schedules of reinforcement, points have been the reinforcers used (Baron et al., 1969; Catania et al., 1982; Hayes et al., 1986; Weiner, 1962, 1969). These same researchers have also suspected that points may be a major uncontrolled variable contributing to their results. This experiment suggests that using sounds as reinforcers may provide researchers with

38 30 useful baselines to study schedule effects, without the need for additional procedures (DRL, response cost, instructions), which may, themselves be possible sources of control and a factor in the difference in response patterns generated between humans and nonhumans.

39 APPENDIX A RECRUITMENT FLYER 31

40 32 Earn Money!' Did you spend too much money over Spring Break? Want to save up money for summer? Just want some extra dough? If so, then this is the way to do it!!! Participate in an experiment on human learning! Call or and leave a message for Susan

41 APPENDIX B INFORMED CONSENT FORM 33

42 34 My name is Susan Rouse and I am a candidate for a Master of Science degree from the University of North Texas. I am asking you to participate in a study, the results of which will be used in my Master's Thesis. Please read the following Informed Consent. The Department of Behavior Analysis supports the practice of protection for human subjects participating in research. The following information is for you to decide whether you wish to participate in the present study. You should be aware that even if you agree, you are free to withdraw at any time without penalty. I am interested in studying the variety of ways people learn. In this experiment you will learn several tasks. These tasks will be presented by a computer and you will learn each of them receiving as much help as you need. There is nothing in the content of these tasks that should make you uncomfortable. It is estimated that this will take between 5 and 10 hours of your time. Although this experience will not directly benefit you, we believe that the results will help clarify a theory attempting to analyze one aspect of how people learn. Your participation is strictly voluntary. You will be paid up to $5.00 per 20 minutes, or sometimes more than $5.00 per 20 minutes. I assure you that your name will not be associated in any way with the research findings. The information will be identified by a code number. If you would like additional information concerning this study before or after it is complete, please feel free to ask anytime. You can reach me at the Department of Behavior Analysis in Chilton Hall #363 or call me at (Department of Behavior Analysis) or at home ( ). You will be given a copy of this consent form. agree to participate in this study. Date Signature of Participant Phone # Date Principal Investigator This Project has been reviewed and approved by the UNT Human Subjects Review Board (940)

43 APPENDIX C FIGURES

44 Figure 1. Experimental Apparatus. 36

45 37 gp^-v-. : «>*, - < *1ZZ: * r <-, s '/ - *<., \ 'vr ; y ^V^'. ::::-:L f,±ilr^ 1 ;;>.\ v./z:.?k; f. s f V' x f? J A III ;, :,y Y? %:ii '<1-. H < / * : : *, o 1 V % s ;* 4 '? s v,,,, ><.. --> - ' r '" - M h '? ^ ^ ' s ^ ' ; ", ', ' Ss - ' < OS 4, lit - " * '' V', ' ' sv 'V -, ' -,ss-" ",, - ^ " ss" -,, s ^s «s -, 5' ^ * sf/,s s- /,'. " ^ <," '.,,, s ' > ' ' I...,.,,.?,r T~

46 Figure 2. Change in apparatus when target response is made. 38

47 39 "^Xt*?^-*-.,< > A: *- - - *' ^ ;- '.*' '* ^' : -'*V - : V \Z;:-^X<:H v { *\?v -' :;.wl&x'f,a... 4-'* />; -Y, '4 \;-_ :r : s ;;v\ A v - ;> w'-i

48 Figure 3. Cumulative Records for Subject JTSP99. 40

49 41 sasuodsey CO H CD z CD CL O CO DL h- i D T DC CO Q Z 3 O CO DC U-

50 Figure 4. Cumulative Records for Subject LSSP99. 42

51 s0suods9y o> CD CL CO CO f2 z O GL CO Q Z Z> O CO

52 Figure 5. Standard Celeration Chart for subjects in Experiment I. 44

53 45 Q. CO CO < Q GC < Q Z HI I < O ill > CO CO LU O o D CO O 3inNii/\i y a d i n p i o o

54 Figure 6. Acquisition for subjects in Experiment II. 46

55 47 8 (/) 0 s0suods9y \ CO Q Z 3 O CO DC LL o> o> DL co CD CD CL CO GQ DQ

56 Figure 7. Cumulative Records for Subject LWSP99. 48

57 49 0 D C sesuodsey o> CD CL C0 CO a z 3 O CO I LO GC CO I- Z 0 CL 1 m DC CO Q Z D O CO m cr U-

58 Figure 8. Cumulative Records for Subject BBSP99. 50

59 51 CO 0 sesuodsey a> a CL C0 CD CD CO Q Z 3 O CO m DC CO O CL t LO DC LL CO Q Z 3 O CO i m cr LL

60 Figure 9. Cumulative Records for Subject LGSP99. 52

61 53 sesuodsay O) CM CO Q 2 D 0 CO 1 LO CC LL CO CM N- CM

62 Figure 10. Standard Celeration Chart for subject in Experiment II. 54

63 55 TJ CD LO >- < Q DC < Q Z HI I < o LLI > (I) CO LU O o =) 05 airinii/m t o d INHOO

64 APPENDIX D TABLES

65 Table 1: Session information for Subject LWSP99 57

66 58 LWSP99 Session Date Condition Responses Rate per Minute Points Money earned FR1 sound $ FR1 sound $ FR5 sound $ FR5 sound $ FR5 sound $ FR5 points $ FR5 points $ FR5 points $ FR5 points $ FR5 sound $ FR5 sound $ FR5 sound $5.00

67 Table 2: Session information for Subject BBSP99 59

68 60 BBSP99 Session Date Condition Responses Rate per Minute Points Money earned FR1 sound $ FR1 sound $ FR5 sound $ FR5 sound $ FR5 sound $ FR5 sound $ FR5 sound $ FR5 sound $ FR5 points $ FR5 points $ FR5 points $ FR5 points $ * FR1 sound $ * FR5 points $ FR5 points $ FR5 sound $ FR5 sound $ FR5 sound $5.00

69 Table 3: Session information for Subject LGSP99 61

70 62 LGSP99 Session Date Condition Responses Rate per Minute Points Money earned FR5 sound $ FR5 sound $ FR5 sound $ FR5 sound $ FR5 points $ FR5 points $ FR5 points $ FR5 points $ FR5 points $ FR5 sound $ FR5 sound $ FR5 sound $5.00

71 Table 4: Post-reinforcement-pause (PRP) data for subject LWSP99 63

72 64 LWSP99 (PRP in looths of a second) Session Date Condition Mean Range FR1 sound FR1 sound FR5 sound FR5 sound FR5 sound FR5 points FR5 points FR5 points FR5 points FR5 sound FR5 sound FR5 sound

73 Table 5: Post-reinforcement-pause (PRP) data for Subject BBSP99 65

74 66 BBSP99 (PRP in looths of a second) Session Date Condition Mean Range FR1 sound FR1 sound FR5 sound FR5 sound FR5 sound FR5 sound FR5 sound FR5 sound FR5 points FR5 points FR5 points FR5 points * FR1 sound 14* FR5 points FR5 points FR5 sound FR5 sound FR5 sound

75 Table 6: Post-reinforcement-pause (PRP) data for subject LGSP99 67

76 68 LGSP99 (PRP in looths of a second) Session Date Condition Mean Range FR5 sound FR5 sound FR5 sound FR5 sound FR5 points FR5 points FR5 points FR5 points FR5 points FR5 sound FR5 sound FR5 sound

77 REFERENCES 69 Baer, D.M. (1960). Escape and avoidance response of pre-school children to two schedules of reinforcement withdrawal. Journal of the Experimental Analysis of Behavior, 3, Baron, A., Kaufman, A. & Stauber, K.A. (1969). Effects of instructions and reinforcement-feedback on human operant behavior maintained by fixed-interval reinforcement. Journal of the Experimental Analysis of Behavior Baron, A. & Leinenweber, A. (1995). Effects of a variable-ratio conditioning history on sensitivity to fixed-interval contingencies in rats. Journal of the Experimental Analysis of Behavior Baron, A. & Perone, M. (1998). Experimental design and analysis in the laboratory study of human operant behavior. In K.A. Lattal & M. Perone (Eds.), Handbook of research methods in human operant behavior (pp ). New York: Plenum Press. Baum, W.M. (1975). Time allocation in human vigilance. Journal of the Experimental Analysis of Behavior. 23, Benton, R.G., & Mefferd, R.B., Jr. (1967). Projector slides changing and focusing as operant reinforcers. Journal of the Experimental Analysis of Behavior